The optiboot bootloader (now used by default on the Arduino Uno) uses only 512 bytes instead of 2K of flash, allowing you to use up to 32256 bytes of your Atmega328P. Furthermore, sketches are loaded with twice the bitrate (115200 instead of 57600).
Ofcourse this works with Jeenodes as well. Just get the optiboot zip file from here:
Extract the zipfile in your sketchbook/hardware folder, restart the IDE. From the Tools->boards menu select the [optiboot] version of the Duemilanove /w Atmega328P.
You can now load the bootloader with from the Arduino IDE using the flash board (http://cafe.jeelabs.net/lab/fb1) like described in this post from jcw:
Be sure to use the Arduino IDE 0019 or higher or it won't work (I tested this with 0021).
When using avrdude, set the hfuse to 0xDE instead of 0xDA. This must be done because the bootloader now starts from address 0x7e00